* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body {
            background-color: #ffffff;
        }
        /* 导航容器 固定尺寸 1487*70 */
        .main-nav-container {
            width: 1487px;
            height: 70px;
            
            margin: 20px auto 0;
            display: flex;
            justify-content: space-evenly; /* 菜单项中间间距相等 */
            align-items: stretch;
        }
        .nav-item-en {
            position: relative;
            display: flex;
            align-items: center;
            height: 100%;
        }
        .nav-item-en > a {
            color: #ffffff;
            text-decoration: none;
            font-size: 17px; /* 主菜单放大一号 */
            padding: 0 12px;
            height: 100%;
            display: flex;
            align-items: center;
        }
        .nav-item-en > a:hover {
            background-color: #253C75;
        }
        /* 下拉菜单：加宽，禁止文字换行 */
        .dropdown {
            position: absolute;
            top: 70px;
            left: 0;
            background: #ffffff;
            min-width: 280px;    /* 加宽适配长英文 */
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
            display: none;
            z-index: 999;
        }
        .dropdown a {
            display: block;
            padding: 12px 18px;
            color: #333333;
            text-decoration: none;
            font-size: 16px; /* 二级菜单放大一号 */
            white-space: nowrap; /* 强制单行，禁止换行 */
        }
        .dropdown a:hover {
            background-color: #f0f3f8;
        }
        .nav-item-en:hover .dropdown {
            display: block;
        }